/*
 * Copyright (C) 2008 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect.testing.testers;

import static com.google.common.collect.testing.Helpers.mapEntry;
import static com.google.common.collect.testing.IteratorFeature.MODIFIABLE;
import static com.google.common.collect.testing.IteratorFeature.UNMODIFIABLE;
import static com.google.common.collect.testing.features.CollectionFeature.ALLOWS_NULL_VALUES;
import static com.google.common.collect.testing.features.CollectionFeature.KNOWN_ORDER;
import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_ITERATOR_REMOVE;
import static com.google.common.collect.testing.features.CollectionSize.ZERO;
import static java.util.Arrays.asList;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.AbstractCollectionTester;
import com.google.common.collect.testing.Helpers;
import com.google.common.collect.testing.IteratorFeature;
import com.google.common.collect.testing.IteratorTester;
import com.google.common.collect.testing.features.CollectionFeature;
import com.google.common.collect.testing.features.CollectionSize;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;
import java.util.NoSuchElementException;
import java.util.Set;

import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@code iterator} operations on a collection. Can't be invoked
 * directly; please see {@link com.google.common.collect.testing.CollectionTestSuiteBuilder}.
 *
 * @author Chris Povirk
 */
@GwtCompatible(emulated = true)
@Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
public class CollectionIteratorTester<E> extends AbstractCollectionTester<E>
{
    public void testIterator()
    {
        List<E> iteratorElements = new ArrayList<>();
        for (E element : collection)
        { // uses iterator()
            iteratorElements.add(element);
        }
        Helpers.assertEqualIgnoringOrder(Arrays.asList(createSamplesArray()), iteratorElements);
    }

    @CollectionFeature.Require(KNOWN_ORDER)
    public void testIterationOrdering()
    {
        List<E> iteratorElements = new ArrayList<>();
        for (E element : collection)
        { // uses iterator()
            iteratorElements.add(element);
        }
        List<E> expected = Helpers.copyToList(getOrderedElements());
        assertEquals("Different ordered iteration", expected, iteratorElements);
    }

    @CollectionFeature.Require(ALLOWS_NULL_VALUES)
    @CollectionSize.Require(absent = ZERO)
    public void testIterator_nullElement()
    {
        initCollectionWithNullElement();
        List<E> iteratorElements = new ArrayList<>();
        for (E element : collection)
        { // uses iterator()
            iteratorElements.add(element);
        }
        Helpers.assertEqualIgnoringOrder(asList(createArrayWithNullElement()), iteratorElements);
    }

    @CollectionFeature.Require(SUPPORTS_ITERATOR_REMOVE)
    @CollectionSize.Require(absent = ZERO)
    public void testIterator_removeAffectsBackingCollection()
    {
        int originalSize = collection.size();
        Iterator<E> iterator = collection.iterator();
        Object element = iterator.next();
        // If it's an Entry, it may become invalid once it's removed from the Map. Copy it.
        if (element instanceof Entry)
        {
            Entry<?, ?> entry = (Entry<?, ?>) element;
            element = mapEntry(entry.getKey(), entry.getValue());
        }
        assertTrue(collection.contains(element)); // sanity check
        iterator.remove();
        assertFalse(collection.contains(element));
        assertEquals(originalSize - 1, collection.size());
    }

    @CollectionFeature.Require({KNOWN_ORDER, SUPPORTS_ITERATOR_REMOVE})
    public void testIterator_knownOrderRemoveSupported()
    {
        runIteratorTest(MODIFIABLE, IteratorTester.KnownOrder.KNOWN_ORDER, getOrderedElements());
    }

    @CollectionFeature.Require(value = KNOWN_ORDER, absent = SUPPORTS_ITERATOR_REMOVE)
    public void testIterator_knownOrderRemoveUnsupported()
    {
        runIteratorTest(UNMODIFIABLE, IteratorTester.KnownOrder.KNOWN_ORDER, getOrderedElements());
    }

    @CollectionFeature.Require(absent = KNOWN_ORDER, value = SUPPORTS_ITERATOR_REMOVE)
    public void testIterator_unknownOrderRemoveSupported()
    {
        runIteratorTest(MODIFIABLE, IteratorTester.KnownOrder.UNKNOWN_ORDER, getSampleElements());
    }

    @CollectionFeature.Require(absent = {KNOWN_ORDER, SUPPORTS_ITERATOR_REMOVE})
    public void testIterator_unknownOrderRemoveUnsupported()
    {
        runIteratorTest(UNMODIFIABLE, IteratorTester.KnownOrder.UNKNOWN_ORDER, getSampleElements());
    }

    private void runIteratorTest(
            Set<IteratorFeature> features, IteratorTester.KnownOrder knownOrder, Iterable<E> elements)
    {
        new IteratorTester<E>(
                Platform.collectionIteratorTesterNumIterations(), features, elements, knownOrder)
        {
            @Override
            protected Iterator<E> newTargetIterator()
            {
                resetCollection();
                return collection.iterator();
            }

            @Override
            protected void verify(List<E> elements)
            {
                expectContents(elements);
            }
        }.test();
    }

    public void testIteratorNoSuchElementException()
    {
        Iterator<E> iterator = collection.iterator();
        while (iterator.hasNext())
        {
            iterator.next();
        }

        try
        {
            iterator.next();
            fail("iterator.next() should throw NoSuchElementException");
        }
        catch (NoSuchElementException expected)
        {
        }
    }
}
